Electrodes for use in displays

ABSTRACT

A liquid crystal display (LCD) is provided having a discontinuous electrode. In certain embodiments, finger- or slit-like extensions of the discontinuous electrode may be shaped to reduce or eliminate disclinations of liquid crystals within a pixel aperture used to transmit light, where the liquid crystals are oriented in response to an electric field generated using the discontinuous electrode. Similarly, in other embodiments, the different portions of the discontinuous electrode may be lengthened to extend under an opaque mask or may not be linked at one end to reduce or eliminate the disclinations.

BACKGROUND

1. Technical Field

Embodiments of the present disclosure relate generally to electrodesused in displays, such as liquid crystal displays.

2. Description of the Related Art

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Liquid crystal displays (LCDs) are commonly used as screens or displaysfor a wide variety of electronic devices, including such consumerelectronics as televisions, computers, and handheld devices (e.g.,cellular telephones, audio and video players, gaming systems, and soforth). Such LCD devices typically provide a flat display in arelatively thin package that is suitable for use in a variety ofelectronic goods. In addition, such LCD devices typically use less powerthan comparable display technologies, making them suitable for use inbattery powered devices or in other contexts where it is desirable tominimize power usage.

The performance of an LCD may be measured with respect to a variety offactors. For example, the brightness of the display, the visibility ofthe display when viewed at an angle, the refresh rate of the display,and various other factors may all describe an LCD and/or determinewhether a display will be useful in the context of a given device. Forexample, with respect to brightness, factors which may affect thebrightness of a display include the area available to transmit light ateach picture element (i.e., pixel) of the display. Likewise, anotherfactor that may influence the brightness of an LCD may be the manner inwhich the liquid crystals forming the display are modulated. Inparticular, such modulation of the liquid crystals determines the amountof light transmitted by a pixel at a given time and artifacts,discontinuities, or irregularities in the fields affecting the liquidcrystals may affect the perceived brightness of a pixel.

SUMMARY

Certain aspects commensurate in scope with the originally claimedinvention are set forth below. It should be understood that theseaspects are presented merely to provide the reader with a brief summaryof certain forms the invention might take and that these aspects are notintended to limit the scope of the invention. Indeed, the invention mayencompass a variety of aspects that may not be set forth below.

The present disclosure relates to increasing the light transmission ofLCD pixels. In accordance with the present disclosure, an electrode of apixel may be shaped or positioned to modify or reduce certaincharacteristics of an electric field generated using the electrode. Forexample, a field characteristic to be reduced may be associated with theimproper alignment or orientation of liquid crystals at specificlocations in the pixel, potentially reducing light transmittance atthese locations. The occurrence or observed effect of suchcharacteristics may be reduced by shaping and/or sizing an electrodeused to generate the electric field.

For example, slat- or finger-like extensions of a pixel electrode may beprovided without a cross-bar at one end of the electrode and/or may beextended further under a mask region of the pixel. Such implementationsmay result in an electric field having improved characteristics withrespect to the manner in which liquid crystals align in the lightmodulating portion of a liquid crystal layer, e.g., the liquid crystalsmay align more uniformly. Similarly, in certain embodiments, theextensions of the pixel electrode may be rounded, curved, and/or angledto affect the characteristics of an electric field generated using theelectrode such that liquid crystals oriented in the field are alignedmore uniformly in the light modulating portion of a liquid crystallayer. In this manner, by shaping and/or positioning portions of anelectrode to account for undesired field effects, more uniform liquidcrystal alignment in the light modulating portion of a pixel may beachieved, and light transmittance through the pixel thereby increased.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present disclosure may become apparent upon readingthe following detailed description and upon reference to the drawings inwhich:

FIG. 1 is a block diagram of exemplary components of an electronicdevice, in accordance with aspects of the present disclosure;

FIG. 2 is a front view of a handheld electronic device in accordancewith aspects of the present disclosure;

FIG. 3 is a view of a computer in accordance with aspects of the presentdisclosure;

FIG. 4 is an exploded view of exemplary layers of a pixel of an LCDpanel, in accordance with aspects of the present disclosure;

FIG. 5 is a circuit diagram of switching and display circuitry of LCDpixels, in accordance with aspects of the present disclosure;

FIG. 6 is a plan view of an LCD pixel in accordance with the prior art;

FIG. 7 is a partial cross section of the LCD pixel of FIG. 6, inaccordance with aspects of the prior art;

FIG. 8 is a plan view of an embodiment of an LCD pixel in accordancewith aspects of the present disclosure;

FIG. 9 is a plan view of another embodiment of an LCD pixel inaccordance with aspects of the present disclosure;

FIG. 10 is a plan view of an additional embodiment of an LCD pixel inaccordance with aspects of the present disclosure;

FIG. 11 is a plan view of a further embodiment of an LCD pixel inaccordance with aspects of the present disclosure;

FIG. 12 is a plan view of another embodiment of an LCD pixel inaccordance with aspects of the present disclosure; and

FIG. 13 is a plan view of an additional embodiment of an LCD pixel inaccordance with aspects of the present disclosure.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments will be described below. Thesedescribed embodiments are provided only by way of example, and do notlimit the scope of the present disclosure. Additionally, in an effort toprovide a concise description of these exemplary embodiments, allfeatures of an actual implementation may not be described in thespecification. It should be appreciated that in the development of anysuch actual implementation, as in any engineering or design project,numerous implementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

The application is generally directed to increasing light transmittancein LCD pixels. In certain embodiments, the increase in lighttransmittance may be accomplished by providing an electrode of a pixelthat is shaped and/or positioned so as to reduce certain characteristicsof a field generated using the pixel. For example, a characteristic ofthe field that may be reduced may be the magnitude of the field in agiven dimension at certain locations. In particular, it may be useful toreduce field components in a given dimension within the portion of aliquid crystal layer used to modulate light transmitted through a pixel.

Example of electrodes that may provide such useful field characteristicsmay include electrodes which do not include a cross-bar to connect slat-or finger-like extensions of the electrode. Likewise, extensions of thepixel may be extended further beneath an opaque mask layer such that thefield characteristics of interest are localized above the opaque maskand not in the portion of the pixel used to modulate light. Similarly,portions of the pixel may be shaped to as to reduce the undesired fieldcomponents or to localize such components away from the region of thepixel used to modulate light.

With these foregoing features in mind, a general description of suitableelectronic devices using LCD displays having such increased lighttransmittance is provided below. In FIG. 1, a block diagram depictingvarious components that may be present in electronic devices suitablefor use with the present techniques is provided. In FIG. 2, one exampleof a suitable electronic device, here provided as a handheld electronicdevice, is depicted. In FIG. 3, another example of a suitable electronicdevice, here provided as a computer system, is depicted. These types ofelectronic devices, and other electronic devices providing comparabledisplay capabilities, may be used in conjunction with the presenttechniques.

An example of a suitable electronic device may include various internaland/or external components which contribute to the function of thedevice. FIG. 1 is a block diagram illustrating the components that maybe present in such an electronic device 8 and which may allow the device8 to function in accordance with the techniques discussed herein. Thoseof ordinary skill in the art will appreciate that the various functionalblocks shown in FIG. 1 may comprise hardware elements (includingcircuitry), software elements (including computer code stored on acomputer-readable medium) or a combination of both hardware and softwareelements. It should further be noted that FIG. 1 is merely one exampleof a particular implementation and is merely intended to illustrate thetypes of components that may be present in a device 8. For example, inthe presently illustrated embodiment, these components may include adisplay 10, I/O ports 12, input structures 14, one or more processors16, a memory device 18, a non-volatile storage 20, expansion card(s) 22,a networking device 24, and a power source 26.

With regard to each of these components, the display 10 may be used todisplay various images generated by the device 8. In one embodiment, thedisplay 10 may be a liquid crystal display (LCD). For example, thedisplay 10 may be an LCD employing fringe field switching (FFS),in-plane switching (IPS), or other techniques useful in operating suchLCD devices. Additionally, in certain embodiments of the electronicdevice 8, the display 10 may be provided in conjunction withtouch-sensitive element, such as a touch screen, that may be used aspart of the control interface for the device 8.

The I/O ports 12 may include ports configured to connect to a variety ofexternal devices, such as a power source, headset or headphones, orother electronic devices (such as handheld devices and/or computers,printers, projectors, external displays, modems, docking stations, andso forth). The I/O ports 12 may support any interface type, such as auniversal serial bus (USB) port, a video port, a serial connection port,a IEEE-1394 port, an Ethernet or modem port, and/or an AC/DC powerconnection port.

The input structures 14 may include the various devices, circuitry, andpathways by which user input or feedback is provided to the processor16. Such input structures 14 may be configured to control a function ofthe device 8, applications running on the device 8, and/or anyinterfaces or devices connected to or used by the electronic device 8.For example, the input structures 14 may allow a user to navigate adisplayed user interface or application interface. Examples of the inputstructures 14 may include buttons, sliders, switches, control pads,keys, knobs, scroll wheels, keyboards, mice, touchpads, and so forth.

In certain embodiments, an input structure 14 and display 10 may beprovided together, such an in the case of a touchscreen where a touchsensitive mechanism is provided in conjunction with the display 10. Insuch embodiments, the user may select or interact with displayedinterface elements via the touch sensitive mechanism. In this way, thedisplayed interface may provide interactive functionality, allowing auser to navigate the displayed interface by touching the display 10.

User interaction with the input structures 14, such as to interact witha user or application interface displayed on the display 10, maygenerate electrical signals indicative of the user input. These inputsignals may be routed via suitable pathways, such as an input hub orbus, to the processor(s) 16 for further processing.

The processor(s) 16 may provide the processing capability to execute theoperating system, programs, user and application interfaces, and anyother functions of the electronic device 8. The processor(s) 16 mayinclude one or more microprocessors, such as one or more“general-purpose” microprocessors, one or more special-purposemicroprocessors and/or ASICS, or some combination of such processingcomponents. For example, the processor 16 may include one or morereduced instruction set (RISC) processors, as well as graphicsprocessors, video processors, audio processors and/or related chip sets.

The instructions or data to be processed by the processor(s) 16 may bestored in a computer-readable medium, such as a memory 18. Such a memory18 may be provided as a volatile memory, such as random access memory(RAM), and/or as a non-volatile memory, such as read-only memory (ROM).The memory 18 may store a variety of information and may be used forvarious purposes. For example, the memory 18 may store firmware for theelectronic device 8 (such as a basic input/output instruction oroperating system instructions), various programs, applications, orroutines executed on the electronic device 8, user interface functions,processor functions, and so forth. In addition, the memory 18 may beused for buffering or caching during operation of the electronic device8.

The components may further include other forms of computer-readablemedia, such as a non-volatile storage 20, for persistent storage of dataand/or instructions. The non-volatile storage 20 may include flashmemory, a hard drive, or any other optical, magnetic, and/or solid-statestorage media. The non-volatile storage 20 may be used to storefirmware, data files, software, wireless connection information, and anyother suitable data.

The embodiment illustrated in FIG. 1 may also include one or more cardor expansion slots. The card slots may be configured to receive anexpansion card 22 that may be used to add functionality, such asadditional memory, I/O functionality, or networking capability, to theelectronic device 8. Such an expansion card 22 may connect to the devicethrough any type of suitable connector, and may be accessed internallyor external to the housing of the electronic device 8. For example, inone embodiment, the expansion card 22 may be flash memory card, such asa SecureDigital (SD) card, mini- or microSD, CompactFlash card,Multimedia card (MMC), or the like.

The components depicted in FIG. 1 also include a network device 24, suchas a network controller or a network interface card (NIC). In oneembodiment, the network device 24 may be a wireless NIC providingwireless connectivity over any 802.11 standard or any other suitablewireless networking standard. The network device 24 may allow theelectronic device 8 to communicate over a network, such as a Local AreaNetwork (LAN), Wide Area Network (WAN), or the Internet. Further, theelectronic device 8 may connect to and send or receive data with anydevice on the network, such as portable electronic devices, personalcomputers, printers, and so forth. Alternatively, in some embodiments,the electronic device 8 may not include a network device 24. In such anembodiment, a NIC may be added as an expansion card 22 to providesimilar networking capability as described above.

Further, the components may also include a power source 26. In oneembodiment, the power source 26 may be one or more batteries, such as alithium-ion polymer battery or other type of suitable battery. Thebattery may be user-removable or may be secured within the housing ofthe electronic device 8, and may be rechargeable. Additionally, thepower source 26 may include AC power, such as provided by an electricaloutlet, and the electronic device 8 may be connected to the power source26 via a power adapter. This power adapter may also be used to rechargeone or more batteries if present.

With the foregoing in mind, FIG. 2 illustrates an electronic device 8 inthe form of a handheld device 30, here a cellular telephone. It shouldbe noted that while the depicted handheld device 30 is provided in thecontext of a cellular telephone, other types of handheld devices (suchas media players for playing music and/or video, personal dataorganizers, handheld game platforms, and/or combinations of suchdevices) may also be suitably provided as the electronic device 8.Further, a suitable handheld device 30 may incorporate the functionalityof one or more types of devices, such as a media player, a cellularphone, a gaming platform, a personal data organizer, and so forth.

For example, in the depicted embodiment, the handheld device 30 is inthe form of a cellular telephone that may provide various additionalfunctionalities (such as the ability to take pictures, record audioand/or video, listen to music, play games, and so forth). As discussedwith respect to the general electronic device of FIG. 1, the handhelddevice 30 may allow a user to connect to and communicate through theInternet or through other networks, such as local or wide area networks.The handheld electronic device 30, may also communicate with otherdevices using short-range connections, such as Bluetooth and near fieldcommunication. By way of example, the handheld device 30 may be a modelof an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif.

In the depicted embodiment, the handheld device 30 includes an enclosureor body that protects the interior components from physical damage andshields them from electromagnetic interference. The enclosure may beformed from any suitable material such as plastic, metal or a compositematerial and may allow certain frequencies of electromagnetic radiationto pass through to wireless communication circuitry within the handhelddevice 30 to facilitate wireless communication.

In the depicted embodiment, the enclosure includes user input structures14 through which a user may interface with the device. Each user inputstructure 14 may be configured to help control a device function whenactuated. For example, in a cellular telephone implementation, one ormore of the input structures 14 may be configured to invoke a “home”screen or menu to be displayed, to toggle between a sleep and a wakemode, to silence a ringer for a cell phone application, to increase ordecrease a volume output, and so forth.

In the depicted embodiment, the handheld device 30 includes a display 10in the form of an LCD 32. The LCD 32 may be used to display a graphicaluser interface (GUI) 34 that allows a user to interact with the handhelddevice 30. The GUI 34 may include various layers, windows, screens,templates, or other graphical elements that may be displayed in all, ora portion, of the LCD 32. Generally, the GUI 34 may include graphicalelements that represent applications and functions of the electronicdevice. The graphical elements may include icons 36 and other imagesrepresenting buttons, sliders, menu bars, and the like. The icons 36 maycorrespond to various applications of the electronic device that mayopen upon selection of a respective icon 36. Furthermore, selection ofan icon 36 may lead to a hierarchical navigation process, such thatselection of an icon 36 leads to a screen that includes one or moreadditional icons or other GUI elements. The icons 36 may be selected viaa touch screen included in the display 10, or may be selected by a userinput structure 14, such as a wheel or button.

The handheld electronic device 30 also may include various input andoutput (I/O) ports 12 that allow connection of the handheld device 30 toexternal devices. For example, one I/O port 12 may be a port that allowsthe transmission and reception of data or commands between the handheldelectronic device 30 and another electronic device, such as a computer.Such an I/O port 12 may be a proprietary port from Apple Inc. or may bean open standard I/O port.

In addition to handheld devices 30, such as the depicted cellulartelephone of FIG. 2, an electronic device 8 may also take the form of acomputer or other type of electronic device. Such computers may includecomputers that are generally portable (such as laptop, notebook, andtablet computers) as well as computers that are generally used in oneplace (such as conventional desktop computers, workstations and/orservers). In certain embodiments, the electronic device 8 in the form ofa computer may be a model of a MacBook®, MacBook® Pro, MacBook Air®,iMac®, Mac® mini, or Mac Pro® available from Apple Inc. By way ofexample, an electronic device 8 in the form of a laptop computer 50 isillustrated in FIG. 3 in accordance with one embodiment. The depictedcomputer 50 includes a housing 52, a display 10 (such as the depictedLCD 32), input structures 14, and input/output ports 12.

In one embodiment, the input structures 14 (such as a keyboard and/ortouchpad) may be used to interact with the computer 50, such as tostart, control, or operate a GUI or applications running on the computer50. For example, a keyboard and/or touchpad may allow a user to navigatea user interface or application interface displayed on the LCD 32.

As depicted, the electronic device 8 in the form of computer 50 may alsoinclude various input and output ports 12 to allow connection ofadditional devices. For example, the computer 50 may include an I/O port12, such as a USB port or other port, suitable for connecting to anotherelectronic device, a projector, a supplemental display, and so forth. Inaddition, the computer 50 may include network connectivity, memory, andstorage capabilities, as described with respect to FIG. 1. As a result,the computer 50 may store and execute a GUI and other applications.

With the foregoing discussion in mind, it may be appreciated that anelectronic device 8 in the form of either a handheld device 30 or acomputer 50 may be provided with an LCD 32 as the display 10. Such anLCD 32 may be utilized to display the respective operating system andapplication interfaces running on the electronic device 8 and/or todisplay data, images, or other visual outputs associated with anoperation of the electronic device 8.

In embodiments in which the electronic device 8 includes an LCD 32, theLCD 32 may include an array or matrix of picture elements (i.e.,pixels). In operation, the LCD 32 generally operates to modulate thetransmission of light through the pixels by controlling the orientationof liquid crystal disposed at each pixel. In general, the orientation ofthe liquid crystals is controlled by a varying an electric fieldassociated with each respective pixel, with the liquid crystals beingoriented at any given instant by the properties (strength, shape, and soforth) of the electric field.

Different types of LCDs may employ different techniques in manipulatingthese electrical fields and/or the liquid crystals. For example, certainLCDs employ transverse electric field modes in which the liquid crystalsare oriented by applying an electrical field that is generally in-planeto a layer of the liquid crystals. Example of such techniques includein-plane switching (IPS) and fringe field switching (FFS) techniques,which differ in the electrode arrangement employed to generate therespective electrical fields.

While control of the orientation of the liquid crystals in such displaysmay be sufficient to modulate the amount of light emitted by a pixel,color filters may also be associated with the pixels to allow specificcolors of light to be emitted by each pixel. For example, in embodimentswhere the LCD 32 is a color display, each pixel of a group of pixels maycorrespond to a different primary color. For example, in one embodiment,a group of pixels may include a red pixel, a green pixel, and a bluepixel, each associated with an appropriately colored filter. Theintensity of light allowed to pass through each pixel (by modulation ofthe corresponding liquid crystals), and its combination with the lightemitted from other adjacent pixels, determines what color(s) areperceived by a user viewing the display. As the viewable colors areformed from individual color components (e.g., red, green, and blue)provided by the colored pixels, the colored pixels may also be referredto as unit pixels.

With the foregoing in mind, and turning once again to the figures, FIG.4 depicts an exploded view of different layers of a pixel of an LCD 32.The pixel 60 includes an upper polarizing layer 64 and a lowerpolarizing layer 66 that polarize light emitted by a backlight assembly68 or light-reflective surface. A lower substrate 70 is disposed abovethe polarizing layer 66 and is generally formed from a light-transparentmaterial, such as glass, quartz, and/or plastic.

A thin film transistor (TFT) layer 72 is depicted as being disposedabove the lower substrate 70. For simplicity, the TFT layer 72 isdepicted as a generalized structure in FIG. 4. In practice, the TFTlayer may itself comprise various conductive, non-conductive, andsemiconductive layers and structures which generally form the electricaldevices and pathways which drive operation of the pixel 60. For example,in an embodiment in which the pixel 60 is part of an FFS LCD panel, theTFT layer 72 may include the respective data lines, scanning or gatelines, pixel electrodes, and common electrodes (as well as otherconductive traces and structures) of the pixel 60. Such conductivestructures may, in light-transmissive portions of the pixel, be formedusing transparent conductive materials, such as indium tin oxide (ITO).In addition, the TFT layer 72 may include insulating layers (such as agate insulating film) formed from suitable transparent materials (suchas silicon oxide or silicon nitride) and semiconductive layers formedfrom suitable semiconductor materials (such as amorphous silicon). Ingeneral, the respective conductive structures and traces, insulatingstructures, and semiconductor structures may be suitably disposed toform the respective pixel and common electrodes, a TFT, and therespective data and scanning lines used to operate the pixel 60, asdescribed in further detail with regard to FIG. 5. An alignment layer 74(formed from polyimide or other suitable materials) may be providedbetween the TFT layer 72 and an overlying liquid crystal layer 78.

The liquid crystal layer 78 includes liquid crystal molecules in a fluidshape or suspended in a polymer matrix. The liquid crystal molecules maybe oriented or aligned with respect to an electrical field generated bythe TFT layer 72. The orientation of the liquid crystal particles in theliquid crystal layer 78 determines the amount of light transmissionthrough the pixel 60. Thus, by modulation of the electrical fieldapplied to the liquid crystal layer 78, the amount of light transmittedthough the pixel 60 may be correspondingly modulated.

Disposed on the other side of the liquid crystal layer 78 from the TFTlayer 72 may be one or more alignment and/or overcoating layers 82interfacing between the liquid crystal layer 78 and an overlying colorfilter 86. The color filter 86, in certain embodiments, may be a red,green, or blue filter, such that each pixel 60 corresponds to a primarycolor when light is transmitted from the backlight assembly 68 throughthe liquid crystal layer 78 and the color filter 86.

The color filter 86 may be surrounded by a light-opaque mask or matrix,e.g., a black mask 88 which circumscribes the light-transmissive portionof the pixel 60. For example, in certain embodiments, the black mask 88may be sized and shaped to define a light-transmissive aperture over theliquid crystal layer 78 and around the color filter 86 and to cover ormask portions of the pixel 60 that do not transmit light, such as thescanning line and data line driving circuitry, the TFT, and theperiphery of the pixel 60. In the depicted embodiment, an uppersubstrate 92 may be disposed between the black mask 88 and color filter86 and the polarizing layer 64. In such an embodiment, the uppersubstrate may be formed from light-transmissive glass, quartz, and/orplastic.

Referring now to FIG. 5, an example of a circuit view of pixel drivingcircuitry found in an LCD 32 is provided. For example, such circuitry asdepicted in FIG. 5 may be embodied in the TFT layer 72 described withrespect to FIG. 4. As depicted, the pixels 60 may be disposed in amatrix that forms an image display region of an LCD 32. In such amatrix, each pixel 60 may be defined by the intersection of data lines100 and scanning or gate lines 102.

Each pixel 60 includes a pixel electrode 110 and thin film transistor(TFT) 112 for switching the pixel electrode 110. In the depictedembodiment, the source 114 of each TFT 112 is electrically connected toa data line 100, extending from respective data line driving circuitry120. Similarly, in the depicted embodiment, the gate 122 of each TFT 112is electrically connected to a scanning or gate line 102, extending fromrespective scanning line driving circuitry 124. In the depictedembodiment, the pixel electrode 110 is electrically connected to a drain128 of the respective TFT 112.

In one embodiment, the data line driving circuitry 120 sends imagesignals to the pixels via the respective data lines 100. Such imagesignals may be applied by line-sequence, i.e., the data lines 100 may besequentially activated during operation. The scanning lines 102 mayapply scanning signals from the scanning line driving circuitry 124 tothe gate 122 of each TFT 112 to which the respective scanning lines 102connect. Such scanning signals may be applied by line-sequence with apredetermined timing and/or in a pulsed manner.

Each TFT 112 serves as a switching element which may be activated anddeactivated (i.e., turned on and off) for a predetermined period basedon the respective presence or absence of a scanning signal at the gate122 of the TFT 112. When activated, a TFT 112 may store the imagesignals received via a respective data line 100 as a charge in the pixelelectrode 110 with a predetermined timing.

The image signals stored at the pixel electrode 110 may be used togenerate an electrical field between the respective pixel electrode 110and a common electrode. Such an electrical field may align liquidcrystals within the liquid crystal layer 78 (FIG. 4) to modulate lighttransmission through the liquid crystal layer 78. In some embodiments, astorage capacitor may also be provided in parallel to the liquid crystalcapacitor formed between the pixel electrode 110 and the commonelectrode to prevent leakage of the stored image signal at the pixelelectrode 110. For example, such a storage capacitor may be providedbetween the drain 128 of the respective TFT 112 and a separate capacitorline.

Turning now to FIGS. 6-13, plan and cross-sectional views of pixels foruse in a fringe field switched (FFS) LCD are provided. In FIGS. 6 and 7,a plan view and a partial cross-sectional view of a prior art pixel areprovided depicting a transparent pixel electrode 110 and TFT 112 used asa switch for the pixel. A black mask 88 defines an aperture 150 throughwhich light may be transmitted by the pixel 60. The black mask 88 may beformed from any suitable opaque material, such as opaque polymericcompositions (e.g., plastics), metals, and so forth. In the depictedexample, the pixel electrode 110 is formed over a passivation layer 160(such as a silicon nitride layer) which insulates the pixel electrode110 from an underlying common electrode 168 (FIG. 7). The commonelectrode may be continuous across the pixel or across multiple pixelsand may be transparent to light. During operation, the common electrode166 may function to provide a common voltage, V_(com), across one ormore pixels. In certain embodiments, both the pixel electrode 110 andthe common electrode 166 are formed from indium tin oxide (ITO).

In the depicted example, the pixel electrode 110 is formed so as to havetwo or more spaced apart extensions 162 or projections, e.g., fingers orslits, that span the aperture 150 in the y-direction. In certainembodiments, the pixel electrode extensions 162 may be between about 500Å to about 600 Å in thickness. In the depicted example, the extensions162 are connected at one end of the pixel electrode 110 by a crossbarregion 164 and at the other end of the pixel electrode 110 by a TFTregion 166 proximate to and in contact with the TFT 112.

In the depicted example, the regions linking the extensions 162, i.e.,the crossbar region 164 and the TFT region 166, are adjacent to orextend into the aperture 150 through which light passes through thepixel. Because the pixel electrode is typically formed from atransparent conductive material, e.g., ITO, these portions of the pixelelectrode 110 do not themselves substantially reduce the amount of lightpassing through the aperture 150. However, the electric field generatednear the crossbar region 164 and the TFT region 166 may havecharacteristics that result in disclinations where the liquid crystalsin these regions are not fully or properly aligned. Thus, in portions ofliquid crystal layer 78 (FIG. 4) near the crossbar region 164 and theTFT region 166, the liquid crystals may not align to allow unimpededtransmission of light through the corresponding portion of the aperture150 when such transmission is specified.

In particular, in the example of an IPS or FFS LCD pixel, an transverseelectric field is generated between adjacent pixel electrode extensions162 to orient liquid crystals by application of an in-plane electricfield. That is, electric field components operating in the x-directionare used to orient the liquid crystals. However, areas near the crossbarregion 164 and the TFT region 166 may generate electric field componentsin the y-direction, causing the affected liquid crystals to bemisaligned or poorly aligned with respect to other liquid crystal in thepixel. As a result, light transmission may be reduced near the crossbarregion 164 and the TFT region 166 of the pixel electrode 110.

Turning now to FIG. 8, an embodiment of a pixel 60 is depicted in whichthe pixel electrode extensions 162 are not linked by a crossbar region164. In addition, in the depicted embodiment, the extensions 162 mayextend further under the black mask 88 than in embodiments where theextensions are linked by a crossbar region 162. In such an embodiment,where the extensions 162 extend further under the black mask 88 and/orwhere a crossbar region is not present, portions of the electric fieldrunning in the y-direction may be present, but may be localized to aregion over the black mask 88. In this manner, undesired disclinationsof the liquid crystals may be localized over the black mask 88 wherethey will not interfere with the transmission of light through the pixel60.

Further, FIG. 8 also depicts an example of an embodiment in which theTFT region 166 linking the extensions at the TFT 112 end of the pixel 60is under the black mask 88. That is, the extensions 162 extend under theblack mask 88 at the TFT end of the pixel as well. In this manner,disclinations may be reduced or eliminated at the TFT end of the pixel60 because portions of the electric field having y-direction componentsmay be localized over the black mask 88 in this region as well. Thus, inthis embodiment, it may be possible to improve the transversedirectionality (here in the x-direction) of the electric field over theaperture 150 by moving those portions of the pixel electrode 110 thatcontribute y-direction components of the electric field under the opaqueblack mask 88.

In addition, turning to FIG. 9, in some embodiments the shape of thepixel 110 may be adapted to reduce the generation of field components inthe y-direction and/or to localize such components over the black mask88. For example, in the depicted embodiment, a curved transition 170 maybe employed to shape the electric field generated by the pixel electrode110. In this example, the curved transition 170 (as opposed to aperpendicular, linear transition as depicted in FIG. 6) is employedwhere the crossbar region 164 and the TFT region 166 link the extensions162. Such a curved transition 170 may change the shape of the extensions162 and/or the corresponding linking region at the location wherey-direction field components are generated. Such a curvature may alterthe shape of the associated electric field to reduce the strength of they-direction field components, to reduce in size the region of theelectric field exhibiting such y-direction characteristics, and/or tolocalize such y-direction field characteristics over the opaque blackmask 88.

As depicted in FIG. 10, in another embodiment, the extensions 162 maynot be connected by a crossbar region 164 at the end of the pixel 60away from the TFT 112 and may still use curved edges 172 to change theshape of the electrode extensions 162. In this example, the extensions162 each have a curved edge 172 (as opposed to straight edges) at thetip portion of the extension 162 away from the TFT 112. In oneembodiment, the curved edge 172 is generally under the black mask 88. Inother embodiments, some or all of the curved edge 172 may not be coveredby the black mask 88. Such curved edges 172 may change the shape of theextensions 162 at the location where y-direction field components aregenerated. As previously discussed, such curvature may alter the shapeof a generated electric field to reduce the strength of the y-directionfield components, to reduce the size of the region of the electric fieldexhibiting such y-direction characteristics, and/or to localize suchy-direction field characteristics over the opaque black mask 88.

In another embodiment, such curved regions of the extension 102 may beasymmetric with respect to the primary axis of the respective extension162. For example, turning now to FIG. 11, curved edges 172 may be usedto provide a curved tip that is angled or slanted for some or all of theextensions 162. All or only a portion of the curved edges 172 may becovered by the black mask 88. As noted above, such curved edges 172 maychange the shape of the extensions 162 at the locations wherey-direction field components are generated, resulting in a reduction inthe strength of the y-direction field components of an electric field, areduction of the region of the electric field exhibiting suchy-direction characteristics, and/or a localization of such y-directionfield characteristics over the opaque black mask 88.

Turning now to FIGS. 12 and 13, in further embodiments, the linearity ofeach extension 162 may be broken not by the use of curved edges or tips,but by the use of angled regions 178, such as angled tips, of theextensions 162. Such angled regions 178 may be formed using linearsegments angled relative to the primary axis of the extensions 162 andmay be wholly or partly covered by the black mask 88. Though thedepicted examples do not include a crossbar member 164, in otherembodiments such a linking crossbar 164 may be provided, with the angledregions 178 of the extensions 162 defined by the shape of the transitionregion between extensions 162 provided by the crossbar 164. Such angledregions, as with the curved regions discussed above, may shape anelectric field generated by the electrode 110 to reduce or eliminatedisclinations in the liquid crystals within the aperture 150.

In addition, the transition between extensions 162, such as at TFTregion 166 of the electrode 110, may formed as something other than aperpendicular transition (as depicted in FIG. 6). Instead, other angledor non-perpendicular transitions 180 may be employed in connecting theextensions 162 such that adjacent extensions 162 are not connected by asingle linear segment. The angled or non-perpendicular transitions 180may be wholly or partly covered by the black mask 88. Such angled ornon-perpendicular transitions 180 may shape an electric field generatedby the electrode 110 to reduce disclinations in the liquid crystalswithin the aperture 150, as discussed above.

While the preceding examples describe configurations of pixels for usein a FFS LCD device, it should be understood that these examples are notintended to be limiting in scope and, indeed, the present teachings mayalso be applicable to other types of LCDs, such as in-plane switched(IPS) LCDs or others. Further, for simplicity the present examplesdescribe circuitry in which the pixel electrode 110 is discontinuous(i.e., includes separated fingers or extensions 162) and the commonelectrode 166 is continuous. As will be appreciated, this arrangementmay be reversed or otherwise varied. For example, in certainembodiments, the common electrode 166 may be discontinuous and the pixelelectrode 110 may be continuous. In such embodiments, the extensions(strips, fingers, and so forth) of the common electrode may vary inshape, size, length, and/or transition to achieve the benefits discussedherein. Likewise, in certain embodiments, the relative position of thepixel electrode 110 and the common electrode 166 may be reversed, i.e.,the common electrode 166 may be proximate to the liquid crystal layer 78while the pixel electrode 110 may be further away. In such embodiments,varying the shape, size, length, and/or transitions of the discontinuouselectrode (whether pixel or common) may be performed as described hereinto achieve the results described.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

What is claimed is:
 1. A liquid crystal display (LCD) comprising aplurality of pixels, each pixel comprising: a liquid crystal layer,wherein alignment of a plurality of liquid crystals within the liquidcrystal layer is determined by an electric field; an opaque maskdefining an aperture over the liquid crystal layer; a circuitry layerbeneath the liquid crystal layer, the circuitry layer capable ofgenerating the electric field, the circuit layer comprising: aninsulating layer; a first electrode formed on a first side of theinsulating layer, the electrode comprising two or more finger-likeregions that extend away from a thin film transistor in a firstdirection, wherein respective ends of the two or more finger-likeregions extend beneath the opaque mask and have arcuate shapes, andwherein two or more portions of the two or more finger-like regions aresubstantially straight and parallel, thereby generating substantiallyzero electric field components operating in the first direction withinthe aperture; and a second electrode formed on a second side of theinsulating layer opposite the first side, wherein the second electrodecomprises a common electrode.
 2. The LCD of claim 1, wherein therespective ends of the two or more finger-like regions are connected bya crossbar region.
 3. The LCD of claim 1, wherein the respective ends ofthe two or more finger-like regions are connected by a region proximateto the thin film transistor.
 4. The LCD of claim 1, wherein the LCDcomprises a fringe field switched (FFS) LCD.
 5. The LCD of claim 1,wherein the first electrode comprises a pixel electrode.
 6. The LCD ofclaim 1, wherein respective ends of the two or more finger-like regionscomprise curved edges or curved transition regions.
 7. The LCD of claim1, wherein respective ends of the two or more finger-like regions arenot connected by a linear segment of the first electrode runningperpendicular to the respective ends.
 8. An electronic device,comprising: one or more input structures; a storage structure encodingone or more executable routines; a processor capable of receiving inputsfrom the one or more input structures and of executing the one or moreexecutable routines when loaded in a memory; and a liquid crystaldisplay (LCD) capable of displaying an output of the processor, whereinthe LCD comprises a plurality of pixels, each pixel comprising: a liquidcrystal layer comprising a plurality of liquid crystals whose alignmentis determined by an electric field, wherein the alignment of the liquidcrystals determines the amount of light which passes through the liquidcrystal layer at the respective pixel; an opaque mask defining anaperture over the liquid crystal layer; an electrode formed on a firstside of an insulating layer, wherein the electrode is used to generatethe electric field, the electrode comprising two or more finger-likeregions, wherein respective ends of the two or more finger-like regionsextend beneath the opaque mask and have arcuate shapes, and wherein theelectric field comprises substantially zero electric field componentswithin the aperture that operate in a direction along which the two ormore finger-like regions extend away from a thin film transistor; and acommon electrode formed along a length of a second side of theinsulating layer opposite the first side.
 9. The electronic device ofclaim 8, wherein the electronic device comprises a computer, a cellulartelephone, a television, a gaming system, or a media player.
 10. Theelectronic device of claim 8, wherein the respective ends of the two ormore finger-like regions comprise one or more curved or angled portions.11. A liquid crystal display (LCD) comprising a plurality of pixels,each pixel comprising: a liquid crystal layer, wherein alignment of aplurality of liquid crystals within the liquid crystal layer isdetermined by an electric field; an opaque mask defining an apertureover the liquid crystal layer; and an electrode capable of generatingthe electric field, wherein the electrode comprises two or morefinger-like regions comprising at least one terminal end having anarcuate shape, and wherein the at least one terminal end is disposedunder the opaque mask.
 12. The LCD of claim 11, wherein at least aportion of the two or more finger-like regions are disposedsubstantially under the opaque mask.
 13. The LCD of claim 11, whereinthe at least one terminal end comprises transitions to a crossbar regionor thin film transistor (TFT) region linking the two or more finger-likeregions.
 14. The LCD of claim 11, wherein the electrode comprises a bodyhaving a substantially rectangular shape.
 15. An electronic device,comprising: one or more input structures; a storage structure encodingone or more executable routines; a processor capable of receiving inputsfrom the one or more input structures and of executing the one or moreexecutable routines when loaded in a memory; and a liquid crystaldisplay (LCD) capable of displaying an output of the processor, whereinthe LCD comprises a plurality of pixels, each pixel comprising: a liquidcrystal layer comprising a plurality of liquid crystals whose alignmentis determined by an electric field; an electrode used to generate theelectric field, the electrode comprising two or more finger-like regionscomprising at least one terminal region having an arcuate shape; and anopaque mask substantially overlying the at least one terminal region.16. The electronic device of claim 15, wherein the one or more inputstructures comprise a touch sensitive structure disposed with the LCD toform a touch screen.
 17. A liquid crystal display (LCD) comprising aplurality of pixels, each pixel comprising: an insulating layer; a firstelectrode formed on a first side of the insulating layer; a secondelectrode formed across a length of a second side of the insulatinglayer opposite the first side, the second electrode comprising two ormore finger-like extensions, each having an arcuate end region thatextends beneath an opaque mask, wherein two or more portions of thefinger-like extensions that are not beneath the opaque mask generate anelectric field comprising substantially zero electric field componentsoperating in a direction along which the two or more finger-likeportions extend away from a thin film transistor, and wherein the two ormore portions of the finger-like extensions are substantially parallelwith each other; and a plurality of liquid crystals whose alignment isdetermined by an electric field generated between the first electrodeand the second electrode.
 18. The LCD of claim 17, wherein the arcuateend regions are connected by a crossbar or a region proximate to thethin film transistor.
 19. The LCD of claim 17, comprising an opaque maskdefining an aperture over the plurality of liquid crystals, wherein thearcuate end regions are disposed substantially beneath the opaque mask.20. The LCD of claim 17, wherein the arcuate end regions comprise curvededges.
 21. The LCD of claim 17, wherein the arcuate end regions compriseangled edges.
 22. The LCD of claim 1, wherein the substantially two ormore substantially straight portions of the finger-like regions aresubstantially perpendicular to at least one side of the aperture.